Surface acoustical wave (SAW) devices are piezoelectric electronic components which traditionally are used as narrow band frequency filters, e.g., frequency determining elements in high frequency control applications. During use, an acoustical wave is propagated across the surface of the SAW device.
As is well known to those skilled in the art, to prevent disruption of the acoustical wave, the package for the SAW device (the SAW package) must not contact the propagating surface of the SAW device, i.e. the SAW device must be packaged so that a free space exists over the propagating surface of the SAW device.
One conventional package for a SAW device seals the SAW device in resin leaving an air gap over the propagating surface of the SAW device. However, the use of a resin mold is relatively complex process which increases the cost of the SAW package. Further, as the resin cures air escaping from the air gap passes through the resin forming apertures in the resin. These apertures allow moisture from the ambient environment to enter the SAW package thereby degrading reliability of the SAW package.
One desirable characteristic of a SAW package is the ability to shield the SAW device. Shielding the SAW device prevents radiation emanating from the SAW device from interfering with adjacent electronic components and also prevents radiation from adjacent electronic components from interfering with the SAW device. Shielding the SAW device becomes increasingly important as electronic systems decrease in size and the spacing between SAW devices and other electronic components is reduced.
Accordingly, the art needs a SAW package which does not involve resin molding and which can be fabricated at a low cost. Further, it is desirable that the SAW package prevents the SAW device from emanating or receiving radiation.